The aforementioned mechanisms are used widely in many fields as linear actuators and operate by converting the rotary motion of either the nut or screw into axial motion of the other. In such mechanisms, buttons or blocks are utilized in cutouts provided in the barrel of the nut to return the balls to adjacent turns of the raceway in order to effect a crossover recirculation of the ball train. A crossover button having a body with an axially diagonal crossover recirculation passage in its radially inner face which separates a portion of a pair of adjacent raceway turns into ball path portions and non-ball path portions is disclosed in U.S. Pat. No. 5,622,082, which is owned by the assignee of the present invention and incorporated herein by reference.
Previously, many crossover return buttons or blocks have been fitted into a cutout hole having vertically straight sides with a press fit. When this method of installation of the button or block is utilized, the cutout of the ball nut may be fitted with a pin of a specified diameter to provide "location" for the bottom surface of the button to prevent the button from being pressed too far into the cutout. Once installed, the locating pin needs to be removed.
Another technique uses the same general procedure but instead of a press fit, the button is provided with a slip fit which, after installation within the cutout, is retained in the proper crossover position by an adhesive.
Still another method involves the use of a stepped cutout or opening wherein the crossover button is inserted into the cutout from the interior of the nut to enable the step to locate the button so that the ball threads align with the ball passages and the crossover button.
Other crossover buttons are known which are formed with small radially projecting ears that nest in the helical grooves of the nut to properly locate the return groove of the crossover button and prevent outward removal of the button through the bore. As in the case of the provision of the stepped bores, such buttons having the radial locating ears must be installed from the interior of the nut, thereby complicating the manufacture and assembly of such ball nut and screw mechanisms.